There is a conventional technology for logically separating computing resources, such as servers. For example, there is a technology named cloud computing in which multiple computing resources on a network are used as user's computing resources. In cloud computing, virtual machines (VM) are allocated to different corporations or divisions, and thereby computing resources are separated for each corporation or division.
Furthermore, there is also a technology for creating a client address in a virtual group routing table and for identifying a virtual group of a client by using this table. Furthermore, there is also a technology for determining whether data is to be forwarded or deleted by using information on a MAC address of a terminal for each virtual group.
Examples of the technology for logically separating computing resources include virtual local area network tagging (VLAN tag: IEEE 802.1q standard) and a provider backbone bridge (PBB: IEEE 802.1ah standard). In the VLAN tag, a VLAN ID is embedded in a media access control (MAC) frame header as an identifier of a logical network. Computing resources are logically separated by using the VLAN ID. Furthermore, in the PBB, a service instance identification (I-SID), which is obtained by encapsulating a MAC frame, is embedded in the MAC frame and the computing resources are logically separated by using the I-SID.
Patent Document 1: Japanese Laid-open Patent Publication No. 09-289521
Patent Document 2: Japanese Laid-open Patent Publication No. 10-093610
However, in the above described technology, there is a problem in that a network is not adequately separated.
For example, in the above described technology for identifying a virtual group of a client, a network is not adequately separated if broadcast communication is performed with the broadcast address set in the header of the data to be transmitted. Specifically, in the above described technology for identifying a virtual group of the client, data is transmitted to all ports instead of being transmitted in virtual group units. Similarly, in the technology for determining whether the data is forwarded or deleted, a network is not adequately separated if broadcast communication is performed with the broadcast address set in the header of the data to be transmitted. Specifically, in the technology for determining whether data is to be forwarded or deleted, data is transmitted to all ports instead of being transmitted in virtual group units. This problem is not limited to cases in which a port is connected to a virtual device; it also occurs in cases in which a port is connected to a server device.
Furthermore, in a VLAN tag and PBB, because a VLAN ID or an I-SID is embedded in data to be transmitted, the size of the data becomes large. Accordingly, there is a problem in that a load is applied to the network. Furthermore, the number of identifiers of the logical network to be set in a header of the VLAN tag or the PBB are 4,096 and 16,777,216, respectively. Accordingly, there is a problem in that, in the VLAN tag and the PBB, the number of logical networks to be used is limited. Furthermore, when compared with other communication methods, because high-cost network devices are used in the PBB, there is a problem in that it is difficult to configure a low-cost network.